All this thread is proving that if you hit your head against something hard when either your head or the "Something" is moving a helmet saves more serious injury.
If you can quantify the risk of it happening and its low don’t wear a helmet
If it’s high probably best wearing one.
On a salutary note, my Aunt died through a head injury out walking her 2 dogs, they bolted unexpectedly and pulled her over hitting her head on the pavement.

